Objective:The aim of this study was to detect fungi in infected root canals and possible correlation between penetration of fungi and clinical symptoms and signs. Methods: One hundred and nine cases of canals with necrotic pulp were selected for this study. After smearing, fixing and staining, the root canals were treated with periodic-acid-schiffs (PAS) method. Finally, the samples were observed under a microscope and the clinical data and results of PAS staining were analyzed. Results: The positive rate of PAS staining was 28.44% . Remarkable differences were demonstrated in positive rates between exposed and unexposed canals. There was no obvious correlation between the results of PAS staining and clinical symptoms and signs. Conclusion: Fungi could exist in the root canals which were infected through caries, cuneiform defect and etc.
